Functional transitions and active life expectancy associated with Alzheimer disease

Context: The concept of active life expectancy, the number of years a person can expect to live without disability, is used for the first time, to our knowledge, to examine the effect of Alzheimer disease (AD) on total life expectancy with different degrees of disability. Objectives: To estimate and compare total life expectancy and average duration lived with different degrees of disability, between persons with and without AD. Design: Ten-year prospective epidemiologic study. Setting: A largely blue-collar rural community in Southwestern Pennsylvania. Participants: A population-based cohort of 1201 subjects (at the beginning of follow-up) with a mean age of 75 years. Main Outcome Measures: At age 70 and every 2 years thereafter, among persons with AD and nondemented persons, (1) the total expectancy of remaining life and (2) the duration lived with different numbers of impaired instrumental activities of daily living (IADLs), grouped as 0 to 1, 2 to 5, and 6 to 7 impairments. Results: Alzheimer disease greatly shortened the total life expectancy to a similar extent in men and women, with the most pronounced reduction among those who were younger. Besides their shorter survival, men and women with AD spent more absolute years, and also a greater proportion of their remaining lives, with 6 to 7 IADL impairments than did their nondemented age peers. Nondemented women spent more years with 2 to 5 IADL impairments than nondemented men, while women with AD spent more years with 6 to 7 IADL impairments than men with AD. Conclusion: The concept of active life expectancy adds a useful new dimension to the study of outcomes in AD.